pic-ker, I bet the RF receiver module you are trying to use has no squelch control and the toggling of the receiver output is the data slicer trying to interpret noise. You will have to put some kind of sync and preamble bytes in place before you transmit the data and, if the sync and preamble bytes are not received in order and correctly you should not accept the data. This is the common problem people have when using inexpensive rx and tx modules. Even with more expensive modules the same sync/preamble techniques should be used. Also you should send a computed checksum as the last byte and this checksum should be checked at the receiver end before using the data received.

Dave Purola,
N8NTA